Spring集成第三方类库（以简单集成elasticsearch 5.x版本客户端为例）

  当我们在Spring中使用第三方类库，但是Spring官方又没有提供相应的集成jar包，而我们又希望Spring能够管理它时，此时可以通过实现FactoryBean接口来达到这个目的。为了Spring能够控制第三方类对象的生命周期，我们还可以实现InitializingBean和DisposableBean接口，或者通过在bean注册时声明初始化（init-method）和结束（destroy-method）方法实现。

下面以elasticsearch的TransportClient对象为例，使Spring简单集成5.x版本的transportClient：

import org.elasticsearch.client.transport.TransportClient;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.transport.InetSocketTransportAddress;
import org.elasticsearch.transport.client.PreBuiltTransportClient;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.InitializingBean;

import java.net.InetAddress;

public class ESTransportClientFactoryBean implements FactoryBean<TransportClient>,InitializingBean,DisposableBean {

    private String clusterName;
    private String host;
    private int port;

    private TransportClient client;

    public void setClusterName(String clusterName) {
        this.clusterName = clusterName;
    }

    public void setHost(String host) {
        this.host = host;
    }

    public void setPort(int port) {
        this.port = port;
    }

    public TransportClient getObject() throws Exception {
        return client;
    }

    public Class<?> getObjectType() {
        return TransportClient.class;
    }

    public boolean isSingleton() {
        return false;
    }

    public void destroy() throws Exception {
        if(client!=null)
            client.close();
    }

    public void afterPropertiesSet() throws Exception {
        Settings settings=Settings.builder().put("cluster.name",this.clusterName).build();
        client=new PreBuiltTransportClient(settings).addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName(this.host),this.port));
    }
}

  当注册factoryBean时，实际上注册的是getObject()方法的返回值，可以理解为bean工厂生产bean，而bean的id为factoryBean注册时的id。

下面是注册factoryBean的例子：

@Configuration
@ComponentScan(basePackages = {"com.search"},
        excludeFilters = {@ComponentScan.Filter(type= FilterType.ANNOTATION,value = Controller.class)})
@EnableTransactionManagement
public class RootConfig {

    ...

    //bean的id为transportClient
    @Bean
    public ESTransportClientFactoryBean transportClient(){
        ESTransportClientFactoryBean transportClientFactory=new ESTransportClientFactoryBean();
        transportClientFactory.setClusterName("cluster");
        transportClientFactory.setHost("192.168.1.206");
        transportClientFactory.setPort(9300);
        return transportClientFactory;
    }

    ...
}

然后，需要使用时直接注入，例：

@Autowired
private TransportClient transportClient;